Age‐related changes in the morphology and the distribution of IgA and IgG in the pharyngeal tonsils of yaks (Bos grunniens)

Abstract

To evaluate age-related changes in the morphology as well as the expression and localization of IgA and IgG in yak pharyngeal tonsils, 20 healthy yaks were divided into four age groups [newborn (1-7 days old), juvenile (5-7 months old), adult (3-6 years old) and old (7-10 years old)]. Morphologic characteristics were observed by histological techniques. The expression and localization of IgA and IgG in pharyngeal tonsils were detected by enzyme linked immunosorbent assay (ELISA) and immunohistochemistry, respectively. The results showed that the epithelium of the pharyngeal tonsils included nonreticular epithelium with an intact basement membrane and reticular epithelium with a discontinuous basement membrane and nonepithelial cell infiltration. In newborn yaks, only primary lymphoid follicles were observed in pharyngeal tonsils. In other age groups, both primary and secondary lymphoid follicles were observed, but some of the lymphoid follicles in the old yaks were degenerated.The number of lymphoid follicles increased from the newborn to the adult group and peaked in the adult group, but the number decreased in the old group. In addition, the age-related trends of IgA and IgG protein expression were similar to those of the number of lymphoid follicles. The concentration of

The Distribution Characteristics of IgA and IgG Antibody-Secreting Cells in the Pharyngeal Tonsils of Bactrian Camels of Different Ages

“…Their distribution densities in these four regions were signi cantly decreased in turn (P < 0.05). These results were basically consistent with the reports in dog [16], yak [43] and porcine [45] studies, suggesting that the reticular epithelium of the pharyngeal tonsils is not only an important channel for the uptake and transport of antigens by M cells, but also its subepithelial region is critical for the colonization and the exertion of immune function of IgA and IgG ASCs. The characteristics of wide distribution of IgA and IgG ASCs indicate that they participate in the formation of a complete immune defense barrier.…”

“…Unlike the body's lymph nodes, the pharyngeal tonsils lack the afferent lymphatic vessels supplying substances for immunological stimulation, and their mucosal epithelium, which is often in contact with antigens, is the main site of interaction between the host and the pathogen [43,44]. Notably, the reticular epithelium covering the pharyngeal tonsils contains M cells and other cells to capture antigens, and is the main antigen uptake site of the pharyngeal tonsils [43,44]. B cells inside the pharyngeal tonsils differentiate into several types of ASCs after they are induced by antigens that enter the pharyngeal tonsils through the reticular epithelium [8,9].…”

“…Changes in the distribution densities of IgA and IgG ASCs can re ect the local levels of IgA and IgG antibodies [45]. Several previous studies have reported that the pharyngeal tonsils of human [37], yak [43] and porcine [45] produce more IgG than IgA, but the pharyngeal tonsils of dog [16] and the palatine tonsils of Bactrian camels [54] produce more IgA than IgG. In this study, we found that the pharyngeal tonsils of Bactrian camels produce more IgA than IgG, suggesting that IgA may be an important component of the mucosal immune response in the pharyngeal tonsils of Bactrian camels and play an important protective role in the mucosal immunity of the upper respiratory tract.…”